Combine flour, garlic powder, paprika, and pepper in a large resealable plastic bag. Seal and shake to combine.
Add drained banana peppers to the bag in batches, shaking to coat in between.
Preheat an air fryer to 375 degrees F (190 degrees C) for 5 minutes. Spray basket with nonstick cooking spray.
Place flour-coated pepper rings in a single layer in the basket of the air fryer (this may need to be done in batches). Spray tops with nonstick cooking spray.
Cook for 4 minutes. Shake basket and cook for 4 minutes more.
Using tongs, transfer pepper slices to a serving plate. Serve with ranch or creamy Italian dressing for dipping.